The objectives are to examine the effects of the alpha agonist methoxamine and the alpha antagonist phenoxybenzamine on uterine and umbilical blood flows, maternal and fetal mean arterial pressures and heart rate as well as acid-base status. Accurately timed gestations in Dorset sheep are utilized. At 120-125 days of gestation, electromagnetic flow transducers are placed on pertinent fetal and maternal vessels, and catheters are placed onto the maternal and fetal aorta and inferior vena cava. Leads are exteriorized and the animal is allowed to recover. Experiments are performed at 3-13 days postoperatively.